Are you playing any mp3s with your mIRC? It can be codec related as I have some problems with it (I just can't figure out how mIRC can crash because WMP can play the mp3 with no problem).
So you're using a script, maybe a dll makes it crash ?
Try installing a fresh version of mIRC, and use only the mIRC, without any addons or scripts, I think it won't crash.
